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When steel, concrete, labour or foreign exchange costs rise, the contractor often asks the same question: can the contract price be changed? In a lump-sum project, the answer does not depend only on the size of the increase. The contract date, assumed risk, cause of the increase, remaining work and the contractor’s conduct must be examined together.

This article focuses on a contractor’s request for adaptation in private-law construction contracts. Recalculation of paid progress payments, additional works ordered by the client and price adjustment under public procurement rules are different claims. Separating them at the outset reduces the risk of placing every cost increase in one claim under the wrong legal basis.

Who bears ordinary cost risk in a lump-sum contract?

Under Article 480(1) of the Turkish Code of Obligations, a contractor who agrees a lump-sum price must produce the work for that price. Work requiring more effort or expense than expected does not, by itself, create a right to an increase. An underpriced bid, an incorrect estimate of quantities or ordinary market fluctuation must be distinguished from circumstances that legally justify adaptation.

First check whether the price is genuinely lump sum. Unit pricing, payment based on measurement, an exchange-rate clause or a contractual price-adjustment formula may require a separate mechanism. The price of additional work following a client’s later design change must also be calculated separately from an increase in the cost of the original work.

When does Article 480(2) become relevant?

Article 480(2) permits a request for judicial adaptation where circumstances that were initially unforeseeable, or foreseeable but not taken into account by the parties, prevent performance at the agreed lump-sum price or make it extremely difficult. Not every increase meets this threshold: a reduced profit margin differs from a severe change in the contract’s economic foundation.

The allegation must be made specific: what assumption underpinned the contract, what changed later, and which work items were affected and by how much? Compare pre-contract quotations, actual purchase prices and the cost analysis for the remaining work rather than relying only on a general inflation rate. There is no fixed percentage increase that applies to every case.

Article 138 is the general hardship provision; its relationship with the special rule in Article 480(2) for lump-sum contracts for work requires separate assessment. Their conditions should not be collapsed into one formula. In particular, Article 138 expressly addresses obligations not yet performed or performed with a reservation of rights arising from excessive difficulty.

The contractor’s notice and reservation-of-rights file

A dated, specific notice is important once the problem emerges. Identify the affected work items, cause, financial consequences and proposed solution. Keep evidence that the other party received it. A general statement that “all rights are reserved” is less informative than a document explaining which event gives rise to which claim.

Review progress-payment, payment, final-account and acceptance documents separately. Seeking adaptation for the first time after completion or closing a disputed account without a reservation can create serious risks. However, do not assume that every private construction contract has the same form requirements or the same number of days for objections; the contract and applicable regime matter.

What does a Court of Cassation decision illustrate?

In its decision of 29 September 2025, E.2024/2679, K.2025/3148, the Sixth Civil Chamber of the Court of Cassation considered contractors’ requests for adaptation and payment following stoppages and increased costs on a museum project. The first-instance court had partly allowed the claim; the regional appellate court dismissed it because the conditions for adaptation were not established. The Court of Cassation upheld that decision.

The decision concerned a particular construction project with a public authority; it is not an automatic rejection rule for all private construction contracts. For a contractor, it illustrates that simply alleging delay and increased costs is insufficient. Risk allocation, foreseeability, the impact on the work and the grounds of the claim must each be demonstrated in the file.

Which records should be prepared?

The first part of the file should contain the contract, annexes, bid, technical specifications and price-adjustment and risk clauses. The second should contain supplier quotations at the contract date and subsequent invoices, labour and equipment records. Evidence should show the cost change for work of the same quantity and specification, not merely that prices increased.

The third part is the chronology: site handover, programme, stop orders, design changes, extensions, progress payments and correspondence. The fourth should distinguish completed from remaining work and provide a comparative calculation. Additional work, the contractor’s own delay and general cost increases should not be counted repeatedly within the same loss item.

Procedure, competent court and the enforcement distinction

The first step is an adaptation proposal explaining the calculation and legal grounds. If no agreement is reached, the claim goes to court according to its legal character. An ordinary private-law contract-for-work dispute falls to the civil court of first instance; a commercial dispute under Article 4 of the Commercial Code may fall to the commercial court. Consumer transactions require separate review of the consumer court and special procedure. Public procurement requires separate examination of Law No. 4735 and the contract documents.

For territorial jurisdiction, consider the defendant’s domicile and the place of contractual performance, and separately review any valid jurisdiction or arbitration clause. For a commercial monetary claim or compensation claim, check pre-action mediation under Article 5/A of the Commercial Code, subject to statutory exceptions. Do not assume that a claim solely seeking modification of the contract and a claim for payment have identical pre-action requirements.

An undetermined new contract price cannot be made conclusive simply by issuing an invoice and starting enforcement without a judgment. Separate an existing due receivable from the adapted price you ask the court to determine. Nor does an adaptation notice or lawsuit automatically authorise stopping work; default, security and termination risks require separate assessment.

Time limits and the risks of leaving the contract

Article 480(2) addresses withdrawal where adaptation is impossible or cannot reasonably be expected of the other party, and termination only where good faith so requires. It does not mean that a contractor may abandon the site whenever costs increase. The sequence and consequences of adaptation, withdrawal and termination must be established for the particular contract.

There is no universal rule requiring adaptation within “30 days”. Nevertheless, late notice, completed performance and final settlement may weaken the claim. For monetary receivables arising from a contract for work, examine the five-year limitation period and exception in Article 147(6), together with maturity under Article 149. This is not an automatic safe waiting period for exercising adaptation rights.

During mandatory pre-action mediation, limitation is suspended and forfeiture periods do not run from the application to the bureau until the final record; an already expired period is not revived. Limitation, contractual notice periods and the need to reserve rights during performance are separate matters. The contractor’s file should track all three without treating them as having the same legal consequences.

Sources

This article provides general information; the contract and documents of the individual matter require separate review.

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Lump-sum adaptation: full interactive evidence and procedure guide

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